A chimney is a vertical structure that allows smoke and gases from a fireplace, stove, or furnace to escape into the atmosphere. It is typically made of brick, stone, or metal and is designed to create a draft that pulls air and combustion gases upward. Proper ventilation is essential for safety and efficiency in heating systems. Chimneys can vary in design and size, depending on the type of heating appliance they serve. They often include a flue, which is the inner passage that directs smoke outside. Regular maintenance, such as cleaning and inspection, is important to prevent chimney fires and ensure safe operation.